How much energy is approximately transferred to the third trophic level in a terrestrial ecosystem that has producers utilizing 6,000 kilocalories per square meter per year?

In a terrestrial ecosystem, energy transfer among trophic levels follows the 10% rule, which states that, on average, only about 10% of the energy from one trophic level is available to the next. Producers, or the first trophic level, capture solar energy and convert it into biomass, which is reflected in the given value of 6,000 kilocalories per square meter per year.

When this energy is transferred to the next level (primary consumers or herbivores), only about 10% is passed on, resulting in approximately 600 kilocalories per square meter per year reaching the second trophic level.

Then, when moving to the third trophic level, which consists of secondary consumers (carnivores that eat herbivores), another 10% of the energy will be transferred from the primary consumers. Calculating this yields 10% of 600 kilocalories, which equals 60 kilocalories per square meter per year.

Therefore, the energy transferred to the third trophic level from the primary consumers is approximately 60 kilocalories per square meter per year, making this the correct answer.